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Bicycle Power - How many Watts can you produce?

I love watching the Tour de France each summer and I enjoy watching the coverage and seeing the cyclist's wattage as they race away from the peloton or climb the Alps. By understanding how much power a person can produce, it should give you a good frame of reference on the scale of electric power production!

As I watch the Tour they occasionally display a rider's instantaneous power output on the screen. They are able to do this because the cyclist has a power meter on their bike and this transmits data to the broadcasting network. So just like the TED can monitor my home's power consumption, the bicycle power meter measures a cyclist's power production. This power usually ranges anywhere between 250 Watts if they are just cruising along with the pack, or 400-500 Watts if they are pushing hard up a steep climb. To see another example of a cyclist's power watch this Olympic cyclist power a toaster.

If you were one of the lucky few to read my What's a Watt post (click through the slideshow at the end that I spent waaaaay too much time making) you know that a Watt is an instantaneous measure of power and is a product of force and speed. In electrical terms, the force is Voltage and speed is current (Amps); therefore, electrical power is Voltage * Current. For a cyclist, the force is how hard he pushes on the pedals and the speed is how fast he turns the crank (rpm). The combination of these two things results in the cyclist's power output, which is usually expressed in watts. For more on this topic, see the great FAQ section that has been put together on this page dedicated to bicycle power generation.

The International Cycling Union (UCI) maintains records for the Hour Record, which is an ongoing contest to see who can ride the farthest in one hour. To get a good estimate of the maximum energy a person can produce (these are elite athletes after all), we'll figure out the average wattage of someone competing for the Hour Record, and since it lasts an hour, this average wattage will be the total energy the rider expended over that hour. Therefore, the energy they expend over the time they compete can be presented in Watt-hours.

The current record holder for the Hour Record is Ondrej Sosenka and the website BikeCult.com has an estimate of his average wattage during his Hour Record at 430 Watts! If Ondrej's bike were attached to a bicycle generator and it was super efficient, Ondrej would have been generating enough power to light up 7 60-Watt light bulbs! Since I pay about 10 cents/kWh, if I were to pay Ondrej for the energy he produced over the hour he was pedaling he would have almost earned a whole nickel (430 Watts • 1 hour = 430 Watt-hours = .43 kWh)!

The cycling blogger Alex Simmons has a great article on the current Masters Men (35-39) Hour Record holder Jayson Austin and his power output over his attempt at the Master's record in 2009. Jayson's average power output was 302 Watts over the hour he rode. The year before Jayson tried to go for the record but was only able to produce an average of 241 Watts (he wasnt feeling too well, so you can see his power output decline the longer he rode). The graph of the two attempts can be seen at the right.

As you can see, the best human efforts at producing power over the course of an hour on a bicycle are around 300-400 Watts. To put this in perspective, when my AC is running full blast my house can consume about 4,000 Watts or 4 kW. I would need over 10 of the best cyclists in the world attached to bicycle generators to power my house when it is consuming this much power! While this doesn't diminish the effort of the cyclists, it does demonstrate that powering our future by pedal power doesn't look like an option, unless they want to work for nickels.....

November 2009 issue of Bicycling magazine has an excellent article on human powered bicycle generators that I highly recommend. As someone who is passionate about renewable energy and cycling, I get very excited reading this stuff. The article mentions two companies that are trying to retrofit gym equipment and spin classes to produce and display cyclists power output. ReRev is retrofitting gym equipment to produce clean energy and The Green Revolution is doing something very similar and targeting spin classes. I've wanted something like this in my gym for awhile. I'm not a big fan of spin class currently because there is no feedback on how I'm performing and improving. These companies can provide valuable feedback on your power output AND produce clean, renewable energy for the grid. This is win-win stuff.

Comments

Hello all, I am wondering how many horsepower an average biker can produce. A few friends and I are trying to see if it would be possible to power a tool that we have that has no engine with a bike. But before we build it we want to know if its possible at all.

As we all have such sedentary lifestyles, why not take advantage of the energy we spend in our much needed workouts and use it for other useful purposes? This is never going to be our way out of any energy problems, but it is making use of already 'lost' energy and it would also motivate people working out. Also, it would put things in perspective if people learn that 5 minutes with an electric hair drier is equivalent to about 30 - 35 minutes pedalling. If we would save some energy out of this concienciation effort... that's much more than the energy we'd be able to produce from riding generator bikes.

A normal human being consumes about 100 Joules of energy every second ( 100 Watts of power = 100 Joules / second ) at rest. Over the course of 25 years of existence, that’s about 79,000 Megajoules of energy ( 100 * 3600 seconds * 24 hours * 365.25 days * 25 years ). Enough energy to power 38 Hoover Dams for one second ( Hoover Dam produces 2080 Megajoules every second )

Vern,
It sounds like you are just discussing a simple gearbox. If you increase the gear ratio, your speed increases but your torque decreases. This is essentially what your chain rings do on your bicycle.

One thought about cycling generators and other workout equipment generating electrical power would be to have the inmates of jails and prisons.
spend a manditory number of hours generating power as part of their regular daily routine.